1. Field of the Invention
The invention relates to a continuous steel plate manufacturing facility comprising continuous casting equipment and a rolling line.
2. Description of the Prior Art
FIG. 1 illustrates an example of continuous casting equipment. Molten steel is introduced through a ladle 30 to a tandish 31, and then supplied to a mold 32 through the tandish 31. The molten steel is cast into a certain shape such as a plate in the mold 32. The thus cast steel plate is rolled downwardly by means of a pair of pinch rolls (not illustrated), and then the thus rolled steel plate is bent and horizontally fed out by means of a plurality of rollers 33. Therefore, the plate is cut by a cutter 34 into slabs having a certain thickness, and subsequently the slabs are horizontally fed out. Usually, a line starting from a ladle to a tandish is called a "machine", while a line from a mold to a point downstream is called a "strand". The continuous casting equipment illustrated in FIG. 1 has a single machine and two strands.
FIG. 2 illustrates an example of a continuous steel plate manufacturing facility comprising a continuous casting apparatus and a rolling line. A slab 35 fed from the continuous casting equipment illustrated in FIG. 1 is reheated in a reheater 36 to a predetermined temperature, and is roughly rolled into a bar 38 in a rough milling machine 37. The bar 38 is again rolled into a strip 40 in a finishing mill 39, and then is wound around a down coiler 41. The continuous steel plate manufacturing facility as mentioned above comprising the continuous casting equipment and the rolling line ensures less consumption energy and a smaller number of processing steps.
FIGS. 3A and 3B are plan views each showing layout of a continuous steel plate manufacturing facility comprising two continuous casting apparatuses including a machine and a strand, and a single rolling line. As illustrated, there has been conventionally used a continuous steel plate manufacturing facility including a plurality of continuous casting apparatuses in communication with a single rolling line in order to enhance operating efficiency of the rolling line. For instance, one of such continuous steel plate manufacturing facilities has been suggested in Japanese Unexamined Utility Model Public Disclosure No. 60-181250, "Continuous Thin Plate Manufacturing Facilities", filed by the assignee of the present application.
FIG. 3A illustrates an example of a continuous steel plate manufacturing facility provided with a reheater including a continuous heater furnace 1 such as a walking furnace. Roller conveyers 2 situated in parallel downstream of continuous casting apparatus CC are spaced away from each other by a certain distance such as about 30 m. At the downstream end of the roller conveyers 2, is disposed a slab-transporter 3 for transversely transporting slabs. The slab-transporter 3 transversely transports slabs fed in parallel from two strands to a feed conveyer 1a through which the slabs are to be introduced into the continuous heater furnace 1. The slabs are reheated in the continuous heater furnace 1 while being transversely transported in the continuous heater furnace 1 to a transporting conveyer 1b, and then supplied to a rolling line 4. There are cutters 5 disposed on the roller conveyers 2. Reject conveyers 6a and 6b, for diverting the slabs having been fed on the roller conveyers 2 to the slab-transporter 3, are also disposed on roller conveyors 2.
FIG. 3B illustrates an example of a continuous steel plate manufacturing facility provided with a reheater including a tunnel heater furnace 7. Similarly to the continuous steel plate manufacturing facilities illustrated in FIG. 3A, the roller conveyers 2, which include the tunnel heater furnaces 7, and are situated in parallel, downstream of the continuous casting apparatus CC, are spaced away from each other. At the downstream end of the roller conveyers 2 is disposed a slab-transporter 8 for transversely transporting slabs. The slab-transporter 8 is also provided with the tunnel heater furnace 7. The slab-transporter 8 transversely transports slabs fed in parallel from two strands to a rolling line 4. Thus, the slabs are supplied to the rolling line 4.
However, the above mentioned conventional continuous steel plate manufacturing facility has the problem that the slab-transporters 3 and 8 cannot avoid being quite large in size. Namely, as mentioned earlier, the two continuous casting apparatuses CC are spaced away from each other by a certain distance, for instance, about 30 m. Hence, the slabs have to be transversely transported at least by about 15 m to reach the rolling line 4. In the slab-transporter 3 shown in FIG. 3A, in order to drive roller conveyers provided with the slab-transporter 3, it is necessary to supply electrical power to each of a large number of the rollers, which includes 30 rollers or more, for instance. Thus, about 100 cables have to be transversely transported by about 15 m together with the slab-transporter 3, resulting in the cable bearer having to be quite large in size. In the slab-transporter 8 shown in FIG. 3B, since the tunnel heater furnace has to be transversely transported together with ancillary facilities thereof such as ducts of the heater furnace, fuel and a feeder of a table, the slab-transporter 8 cannot avoid being quite large in size.
There is another problem in the conventional continuous steel plate manufacturing facilities that since the slab-transporters 3 and 8 are large in size, they cannot be transversely moved at high speed, resulting in great temperature reduction of the slabs. Specifically, it takes about one minute for the large-sized slab-transporter 3 to be transversely moved by about 15 m even by a high-powered driver. While the movement of the slab-transporter 3, the temperature of the slabs falls by about 30 degrees, for instance, and thus it takes much time to reheat the slabs and maintain the temperature of the reheated slabs to be homogeneous. Furthermore, much of fuel has to be consumed for reheating the slabs and maintaining the temperature of the slabs homogeneous. On the other hand, the slab-transporter 8 shown in FIG. 3B is able to avoid the temperature fall of the slabs, since the slab-transporter 8 is provided with a heater furnace. However, the slab-transporter 8 has problems that the heater furnace provided makes the continuous steel plate manufacturing facility larger, and facilitates the growth of scales which are difficult to remove.
In addition, since the slab-transporters 3 and 8 take time to transversely move because of their large size, it is difficult to combine the slab-transporter with three or more continuous casting apparatuses, which prevents the enhancement of productivity of the continuous steel plate manufacturing facility.